RU1836655C - A method for application (to a base) of coating being a liquid composition in the form of freely falling curtain - Google Patents

Abstract

Use: for coating materials, including for the manufacture of photographic materials. SUMMARY OF THE INVENTION: in a method of coating a substrate with a free-falling curtain from a liquid composition, wherein the free-falling curtain 12 is delimited along the edges by guides for edges 50, spaced apart from each other by a distance shorter than the width of the substrate 16, and fed to With these guides, the washer fluid, the washer fluid are removed from the edges of the curtain, and a vacuum source is connected to the guides near the contact point of the freely falling curtain with the movable substrate. 4 s.p. f-ly, 11 ill.

Description

The invention relates to a method for coating in bulk on objects or moving substrates that continuously move past a coating station. More particularly, it relates to an improved bulk coating method for the manufacture of photographic materials, in particular photographic film and paper.

. During the bulk coating process, in particular the process for producing multilayer photographic materials, the quality of the coating is largely determined by the properties of the liquid curtain. It is very important to make sure that the same stable laminar outflow of liquid is created using the guide chute

films and what of such a film creates a laminar curtain moving from the liquid. In order to prevent the falling curtain from narrowing due to surface tension, the width of the curtain is known to be kept within the boundaries by means of guides for the edges of the curtain.

Typically, the edge guides are stationary solid elements that are secured to the guide groove used to supply the coating fluid to the curtain and extend from top to bottom from the starting point of the curtain. Throughout the length of the edge guide, wetting contact should be maintained between the edge of the falling curtain and the edge guide to avoid breaking the curtain.

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The guides for the edges of the curtain should be arranged so that the coating is applied to the moving substrate (a) to the edge itself, (c) leaving the edges of the substrate directly uncovered, or (c) so that the coating liquid extends across one or both edges the substrate. During any of these three processes, to stabilize the curtain on the sides of the curtain, it is possible to provide an edge liquid strip, which liquid is collected and returned for reuse.

The edge portions of the film substrate are usually profiled with a thickened wheel, which protects sensitive photographic materials from the increased localized pressure during winding, which is created as a result of the smallest variations in the thickness of the substrate. It is desirable to avoid applying any amount of the coating composition to the embossed areas, since the inherent photographic coating tack at high humidity makes it difficult to unwind the substrate during the final operations.

The ability to keep the embossed edge sections free of coatings is achieved by placing edge guides on the edges of the substrate. However, this leads to the emergence of a huckle border along both edges of the substrate, where fluid collects in the beads. Such edges must be cut to obtain a completely uniform coated substrate. However, before an expensive and wasteful shearing operation, such excessively thick flanges of the coating liquid can have an undesirable effect on the effectiveness of the drying agent, which leads to the contamination of the transport rollers below.

A method is known in which the lower ends of the edge guides (see FIGS. 7 and 8) extend to a trawl brush or a thin strip of flexible material that helps distribute the excess covering liquid (edge bands of liquid and excess liquids) near the edge of the coating. the guiding devices soon become contaminated, retain the specks and the dried coating solution and very quickly become ineffective in obtaining free areas in the embossed areas of the substrate material, and especially when they are used in a continuous coating process, neobhodi0

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for the manufacture of photographic material.

The essence of the present invention lies in the fact that the method of coating a substrate from at least one layer of a liquid composition involves moving the substrate along a path through the coating zone, creating a freely falling curtain in the coating zone that extends perpendicular to the path and comes into contact with the moving substrate, forming a coating on it, and this freely falling curtain is in wetting contact with the edge guides, spaced apart from each other by a distance that is less the width of the substrate to be coated. These edge guides are connected to a suction device located close to the point of contact of the falling curtain, whereby liquid from the curtain is removed from the edges of the curtain before this curtain comes into contact with the substrate.

The width of the coating inside the edges of the substrate can be optimized in accordance with the desired product requirements. The production process with no coating on the edges can be brought about with high efficiency, which allows to reduce the amount of waste material, since the amount of unused substrate material is reduced.

Coating within the edges of the substrate allows embossed edge portions to be free of coating material.

When coating over the edges of the substrate, in order to prevent the coating material from getting onto the surface of the support rollers, it is necessary to use a coating roller whose width is less than the width of the coating. Thus, in order to adapt to the specific width of the substrate to be treated, a particular replacement of the coating rollers is required. The implementation of the present method allows the use of a support roll of universal width, since all the coating material is inside the edges of the substrate.

In accordance with the present invention, defects associated with fouling and peeling, which are characteristic of the brush technology as previously known, are prevented.

The application of the present method also eliminates the use of prefabricated pallets along each side of the coating area that were previously considered unavoidable to remove excess

fluid curtains in the sections of the edge rails.

The aforementioned advantages make it possible to achieve increased reliability of the bulk coating process in combination with improved utilization of the equipment and significant removal of redundant equipment.

The essence of the method of the present invention and the apparatus for implementation are illustrated by the accompanying drawings.

In FIG. 1 is a simplified axonometric view of a bulk coating apparatus with a guiding funnel; in FIG. 2 is a cross-sectional view showing a surface of a continuous edge guide element being washed by a fluid stream; in FIG. 3 is a cross-sectional view of an edge guide element with a slit using washer fluid; in FIG. 4 is a vertical section through a continuous edge guide element and a falling curtain extending beyond the edge of a moving substrate; in FIG. 5 is a vertical sectional view of a portion of a continuous edge guide element mounted inside the edges of a moving substrate in accordance with the prior art; in FIG. 6 is a simplified axonometric view of a bulk type coating device with a guide chute; in FIG. 7 is an incomplete vertical section showing a fluid removal point in which a solid edge guide element is used; in FIG. 8, 9 are partial cross-sectional views in a three-dimensional image showing points of fluid removal; in FIG. 10 is a three-dimensional view of a washer fluid supplied to the upper part of the edge guide element with a slit; in FIG. 11 - in a three-dimensional image, the washing fluid supplied to the side of the edge guide

element with a slot.

According to FIG. 1, the coating liquids are laterally fed into the guide chute 1, ascending to the exit slots 2, and applied in the form of a layer on individually inclined surfaces 3. Under the influence of their own weight, the individual layers flow down to the surfaces 3i flow one above the other and move towards the coating edge 4, where a free-falling curtain 5 is formed. This guide chute can have any desired width, in particular from a few inches to several pounds. 5. A free-falling complex curtain 5. which passes

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perpendicular to the path of movement of the substrate 6, drop in height h and comes into contact with the continuously moving substrate 6 to form a composite of layers. At the point at which the curtain 5 comes into contact with the substrate, it is preferable to direct the substrate b towards and around the coating roller 7. The width of the coating roller may be less than or greater than the width of the substrate 6 guided around this roller, depending on the technique for making the edges. The coating roller 7 is mounted on an electric motor and this roller can be driven from it.

Layers of the photographic coating composition can be applied to various substrates. Typical photographic substrates include polymer films, wood fiber, for example, in the form of paper, metal sheet material and foil, glass and ceramic substrates provided with one or more auxiliary layers to improve adhesion, anti-static, size-resistant, abrasive, hardness functional, anti-rheological and / or other properties of the substrate. Coatings on materials can be applied using separate sheets or. more commonly, a continuous substrate.

The freely falling liquid curtain 5 from the blocks is guided by two edge guides 8 and 8, which are oriented vertically and are designed to hold and stabilize the freely falling one until it comes in contact with the substrate 6. The edge guides can be installed in this way so that a coating whose width is less than the width of the substrate is applied to a moving substrate to be coated.

In order to maintain the stability of the free-falling curtain at the edge guide portion, a low viscosity liquid may be provided to the edge guide for the purpose of achieving a flush effect of the outer surface of the solid edge guide.

In FIG. 2 is a cross-sectional view of a free-falling curtain 5, which shows a continuous guide for the edge 9, washed by the washing liquid 10, located between the edge guide and the photographic fluid 5. Washing the outer surface of the edge guides also prevents soiling these edge guides with a dried coating composition. Since the thickness of the curtain 5 is approximately (1.5-4.0) m. And the diameter

the edge guide is approximately (0.7-3.0) m, the washing fluid 10 forms a meniscus 11 around the edge guide due to the existence of surface forces. In order to obtain meniscus 11, the fluid is drawn from the falling curtain near the edge guides, as shown by the thinner section 12.

A drawback of the flushing effect of the outer surface of the solid edge guide is that it causes instability of the falling curtain due to the existence of this region of thinning t2.

In order to maintain the stability of the free-falling curtain in the region of the edge guides, a low viscosity washer fluid may be provided into the hollow edge guide with a slit.

In fig. 3 is a cross-sectional view of a free-falling curtain that shows an edge guide with a slit 13, the washer fluid 10 being introduced into the guide edge and fed to laterally recharge the edges of the falling curtain through the slit 14. The washer fluid 10 may be inert low viscous liquid, for example, a clear gelatin solution or water. Since the parameters of the slit are characterized by the same order as the thickness (1.5-4.0) m, the fastening zone of the curtain is provided by the sharp corners of the slit, so that the washing liquid does not form a meniscus to the edge guide, as is the case in the case when the solid guide for the edge 9 is washed off, as described in Fig. 2. Thus, in the case of a guide for the edge with a slit, the thickness of the falling curtain 5 remains constant over the entire width, which makes it possible to achieve curtain stability and uniformity of the coating.

In FIG. Figure 4 shows an image of a solid edge guide in the area where the freely falling curtain comes into contact with the moving under the spoon. The washer fluid 10 near the edge guide and the fluid strip in the region of the lip 15 near the washer fluid 10 are shown entering the collection tank 16, which leads to a drain (not shown). It can be seen that each curtain wets the back side of the substrate 6 at the edges of the substrate, in section 17. and also covers the embossed sections 18. The liquid that covers the back of the substrate is transferred to the last

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conveying rollers, as a result of which it is sometimes necessary to terminate the coating process in order to clean subsequent conveying rollers. The coating applied to the embossed sections 18 causes problems in the finishing process due to the stickiness of the gelatin and the high winding pressures due to knurling.

In FIG. Figure 5 shows an image of a solid guide for an edge in the contact area of a freely falling curtain and a moving substrate 6, where the width of the curtain is less than the width of the substrate.

g Washer fluid 10 near the edge guide and photographic fluids of the falling curtain 5 near the washer fluid are coated onto the moving substrate 6 within the embossed zone 18. Due to the low covering power, low viscosity and high velocity of the washer fluid 10 per In the area where the washer fluid 10 comes into contact with the moving substrate behind the curtain, a sag 19 is formed. This sag 19 is a result of poor wetting and displaces the solution 20 from the sag zone to an adjacent zone, due to e thereby increasing the number of steerable product waste. In FIG. 6, the guide coating chute 1 is provided with two supports fixed thereto, provided with slotted guide tubes for the edges 21, which are arranged so that the width of the coating

5 is smaller than the width of the substrate 6. The free-falling composite curtain 5 extends across the path of movement of the substrate 6, falling from a height h, and comes into contact with the continuously moving substrate 6, thus forming a multilayer coating. In a preferred embodiment, the substrate 6 should be directed to and around the coating roller 7 in that area where the curtain 5 comes into contact with the substrate. A low-viscosity washer fluid 10, preferably water, is fed into the upper part of the guide with a slit for the edge 21 and it is distributed over the entire height of the guide for the edge from the edge of the coating 4 to the point where

0, the edge guides bend upward immediately above the point at which the liquid curtain 5 meets the substrate 6. The liquid of the curtain is removed from the edge zone of the falling curtain until the thickness decreases significantly beyond its edge zone by connecting the end of the inner guide for the edge 21 s a suction device 22, preferably near the contact area of the falling curtain. 5 removed liquids

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the balance is discharged to a storage tank remote from the coating area.

In FIG. 7 is a partial vertical section illustrating the possibility of combining a vacuum source 23 with a solid guide for the edge 24 in accordance with another embodiment of the present invention. The diameter of the solid guide for the edge 24 can be in the range of about 0.15 to 3.0 m, and this guide is washed by a low-viscosity washer fluid 10 and is installed on the side of the non-guiding falling curtain 5. The solid guide for the edge 24 is set to the immediate vicinity of the spur 6 at a distance of L. which is in the range from 0.2 to 10 ..

An opening 25 is provided at the lower end of the guide for the edge 24 near the area where the falling curtain comes into contact with the moving substrate. This hole extends through this end. In a preferred embodiment, the diameter of the outlet 25 is from 0.35 to 2.4 um.

To drain the curtain liquid from the edge portion of the falling curtain, the hole 25 is connected to a vacuum source 23, the magnitude of which is from about 1.23 to 9.84 kPa. The location of the hole 25 should allow for the removal of almost all of the wash fluid 10. which is used to flush the edge guide. The diameter of the outlet hole 25 in the solid edge guide and the suction rate to remove the liquid can be controlled until the amount of washing liquid discharged from the edge portion of the falling curtain creates a certain layered profile to the area of the edge of the coating, about which witnessing the observation of section 26 without the undesired sag formation referred to in connection with FIG. 5.

The amount of washer fluid discharged from the edge portion of the falling curtain, obviously, depends on the rate of outflow of the washer fluid, the flow rate of which can vary in the range of - approximately from 0.833 to m3 / s. It has been found that the process of removing washer fluid from the edge portion of a free-falling curtain is independent of the flow rate of the liquid of the falling curtain and the coating speed, which can vary from 1 to 7 m / s.

The passage of the hole 25 in the solid guide for the edge 24 is not

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is critical, but to achieve the effectiveness of the preferred embodiment, it should be (0.2-1.2) 10 m from the site of collision of the curtain 5 with the substrate 6. Removing the hole 25 up more than the maximum, the distance causes a smaller the effectiveness of the edge guide in stabilizing the curtain and removing the contaminants mentioned above. Instead of a round one, a hole of any cross section can be used, in particular an elongated, slit-like or a set of several smaller holes, the total cross section of which is equal to that necessary to remove the washing fluid. In the case where the apparatus of the present inventor, a variant of which is described in connection with FIG. 7 operates in the preferred ranges of the parameters indicated above, there is no instability of the falling curtain along the entire length of the edge guide. By adjusting the suction rate and cross-sectional area

5 holes 25 in the washed continuous guide edge together with the flow rate of the washing liquid provides the creation of a certain section of the layered edge of the composite coating 26.

0 This edge can be effectively dried with photographic coating.

In FIG. 7 washer fluid functions 10 combined with edge function

5 of the fluid cavity 15 supplied to the edge portions of the curtain to increase the stability of the curtain. Typically, when using an edge strip of liquid, a supply of an edge strip of liquid to the edges of the guide channel is good in an amount sufficient to achieve the thickness of the curtain and. therefore, the flow rate of the strip of edge fluid., which slightly exceed

with the thickness and flow rate of the liquid in the central curtain, which allows to increase the stability of the curtain after the guides for the edges and, therefore, to avoid breaking the curtain. It must be borne in mind that the width and thickness of the edge strip of liquid

0 curtains are such that relatively large amounts of washer fluid may be required. The process gives good results when the viscosity of the edgeband fluid

5 approaches the viscosity of the liquid applied by a central coating curtain. Gelatinous solutions of suitable concentration with added wetting agents are acceptable.

In the case when the coating is applied using an edgeband fluid, the coating thickness of this edgeband fluid should not substantially exceed the rest of the coating, which allows efficient drying of the entire coating as a whole. Almost all of the wash liquid 10 is removed from the edge of the curtain.

In FIG. 8 is a partial sectional view of a detailed image that illustrates the source of vacuum associated with the edge guide to the slot 27. The slot 28 extends in such a way as to provide lateral washing with liquid 10 of the edge of the falling curtain 5.

Slit 28 extends along the entire length of the guide for the edge 27 from a point near the edge 4 of the guide gutter, from where the curtain 5 begins its free fall to a point near the line of collision of this curtain with the substrate. The guide for the edge with a slit 28 is spaced L away from the substrate, which is in the range of about 0.2 to 10 m. At the bottom, the guide with a slit for the edge 27 is muffled, and its outer diameter is approximately (0, 75- 3.0) 10 m. And the inner diameter is approximately (0.35-2.4) m. The width of the slit 28 in the guide tube for the edge is approximately consistent with the thickness of the falling curtain, given that the thickness of the curtain during free falls are constantly decreasing. It was found that a slit width of approximately (0.7-4.0) 10 m was satisfactory for most values of the curtain fluid flow rate. It is clear that the curtain fluid flow rate can be varied over a wide range depending on the coating speed and thickness coating, whereby it may be necessary to adjust the width of the slit to create conditions for the formation of various curtains.

Observations of the guide with a slit for the edge 27 after the formation of the curtain showed that the washer fluid 10 does not wet the outer surface of the guide tube for the edge. The outer surfaces of the falling curtain were connected with the corners that formed a gap with the outer surface of the tube (see Fig. 3), while in the case of washing the outer surface of the solid guide for the edge with the washing fluid, most of the outer surface is wetted by the washing fluid (see Fig; 2). The use of slotted guides for the edges that connect the curtain to the corners of the slots increases the stability of the curtain.

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It has been found that in the case where the suction source 29 is connected to the outlet 30 near the end of the slotted edge guide, it is possible to remove a substantial portion of the washer fluid 10 directed towards the curtain at the top of the tube. The diameter of the outlet hole 30 should preferably be (0.35-2.4) m and it should extend opposite the lower boundary of the slot 28, with the lower end of the tube 31 being plugged,

The calculation of the flow rate of the flow of the current medium showed that most of the washing fluid .10 is removed at the last centimeter of the gap, near the end of the free fall of the curtain. By creating suction sources of sufficient vacuum, for example, at a residual pressure of (1.23-9.84) kPa, it is possible to practically remove the entire washing fluid 10 and even a small amount of curtain fluid. By adjusting the vacuum level of the suction source and the flow rate of the washer fluid, which can vary from about 1.66 to 0.333 m3 / s, different amounts of washer fluid can be removed.

It was found that with adequate removal of the washing fluid, the edge portion of the coating is free from a thickened edge, which allows a certain layered profile of the coating compositions to be achieved, as illustrated by 26. The implementation of the method of the present invention, in particular when using slotted guides for edges with a suction source to remove at a point near the contact line of the curtain, provides an exceptionally stable curtain that can provide a coating inside the edges of the substrate and, whereby the edge portion is characterized by a coating with a defined layered profile. In order to maintain the stability of the curtain, it may be desirable to apply a small portion of the washing liquid along with the coating. The amount of washer fluid applied to the substrate should be kept to a minimum so as to avoid insufficient wetting due to the sagging process discussed above.

In FIG. Figure 9 shows a slit tube 21 provided with a slit of a curved configuration 32 and an outlet 22 for a vacuum source. In a preferred embodiment, the internal bending radius of the slotted tube should be approximately (0.300-1.20) m. Slit 33 extends along the entire length of the guide for the edge 21 from a point near the edge of the guide trough, from where the curtain 5 begins to fall freely to the point near the line of entry of this curtain into contact. The slit tube 21 is positioned so that the bottom of the tube itself is spaced L away from the substrate, which may vary from approximately (0.002-1.0) m. The outer diameter of the tube 21 is approximately (0.075-0.300) 10 m, and the inner diameter is approximately (0.035-0.240) 10 m. The width of the slit 33 is approximately consistent with the thickness of the falling curtain, taking into account the constant thinning of the curtain as it falls freely. It was found that a gap of approximately (0.007-0.40) 10 m was satisfactory for most of the curtain fluid flow rates. The use of slit tubes for edges that connect the curtain to the corners of the gap also appears to increase the stability of the curtain. The lower edge of the gap 33 should be located in the range of at least 0.450 m from the lowest part of the slotted tube 21.

It was found that in the case when the suction source 22 with a residual pressure of approximately (0.209-1.67) 10

kPa connected to the end of a curved slot

T

of the tube 21, it is possible to remove a substantial portion of the washer fluid 10 supplied laterally into the curtain through a slit. Most of the washer fluid 10 removes slits on the last centimeter directly at the end of the free fall of the curtain. By adjusting the vacuum level of the suction source and the flow rate of the washer fluid, it is possible to vary the amount of washer fluid 10 removed, as well as small amounts from the edge portions of the falling curtain 5, Thus, the implementation of this option allows you to create a highly stable curtain, which makes it possible to apply on the substrate, coating inside the edges to form a coating with a defined layered profile, which is shown in zone 26.

In accordance with

FIG. 10, a low viscosity washer fluid 10 is fed into the upper part of the slot guide for the edge 27 and is distributed over the entire height of the guide for the edge from the edge of the coating 4 to the point where the slot 28 ends directly above the point where the liquid the curtain collides with the backing. Washer fluid 10 passes through the gap 28 in the same plane as the curtain, and on the side of it and adjacent to the covering fluids from 5

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5, when this curtain begins its free fall at the edge of the coating 4.

The width of the gap has a significant effect on the flow rate and speed of the washer fluid coming from that gap. From comparing the cross-sectional area of the guide tube for the edge with the area of the slit (length times width) in the embodiments illustrated in Figs. 8 and 9, it is obvious that the area of the first centimeter of the gap exceeds the cross-sectional area of the tube through which the washer fluid enters. It was found that satisfactory results were achieved using a tube with an outer diameter of 0.2 m and an inner diameter of 0.10 m with a slit width of 0.02 m. The area on the first centimeter of the slit was 0.02 10 m, while the cross-sectional area of the tube is 0.008 m2. Fluid flow calculations have shown that most of the washer fluid flows out a first centimeter along the length of the gap.

Thus, almost the entire washing liquid flows to the curtain at or near the edge of the gutter, from where the curtain begins to fall freely. Only a small amount of washer fluid is required, for example, a flow rate of from 1.667 to 0.333-10 m / s, as a result of which the width of the washer fluid coming from the slot next to the curtain is only a few millimeters. Since most of the washer fluid flows along the first centimeter of the edge guide where the curtain is just starting to accelerate, almost all of the washer fluid is supplied along the entire length of the curtain's free-fall path. This maximizes the effectiveness of the low viscous washer fluid in reducing the velocity gradient of the curtain near the edge slit guides, thereby increasing the stability of the curtain in the zones of its edges.

Thus, the washer fluid 10 enters the curtain along its edges in an amount that depends on the viscosity of the washer fluid, flow rate and gap width, and this fluid moves until it reaches a removal point where it is aspirated near the collision site a falling curtain with a backing as indicated above.

In FIG. 11, however, is yet another embodiment of the slotted guide tube for the edge 34, which is positioned so as to direct laterally the free fall of the curtain 5, as described above for the slotted guide for the edges 27 described in connection with FIG. 10 The guide edge 34 is located above the edge of the coating 4, where the curtain comes into contact with the washing fluid 10 coming from the slot 35. In order to prevent undesirable defects at the edge of the falling curtain and to ensure uniform distribution of the washing fluid throughout th slot height at the edge of the preferred embodiment of feed tube 36 must be located above the beginning of the gap 35.

Advantages of the method proposed in accordance with the present invention, using the edge guiding designs shown in fig. 7, 8, and 9, for the manufacture of photographic material, is illustrated by way of example. A device for directional coating of this type, as shown in fig. 6 is provided with guides for edges of the type shown in fig. 7, 8 and 9 to obtain a three layer coating.

The free fall height of the curtain h was 0.25 m. And the point of contact between the curtain and the substrate, commonly referred to as the application point, was defined as the midpoint of the coating roller. When referring to this description, the point of application refers to the angle (either positive or negative), at which the plane, determined by the free fall of the curtain, deviates from the middle point of the coating roller on which the substrate is transported.

A three-layer photographic coating composition was used consisting of aqueous gelatin with a viscosity of 30 cP for the lower layer. 50 cP for the middle layer and 70 cP for the upper layer. The material flow rate for the three-layer composite coating was 4-10 m3 / s.

Example p. The solid rod guide for the edge illustrated in Fig. 7 was mounted vertically so that the width of the coating was less than the width of the substrate. A 0.023 m thick polyethylene coated paper substrate was used as the substrate. An aqueous solution was used to rinse the outer surface of the solid core guide for the edge according to the known method. An edge strip of liquid was supplied to the edge portion of the curtain. The outlet is connected to a vacuum source.

2.0 10 7m3 / s 0.075

v2

The outer diameter of the solid bar is a guide for the edge .0,150.

Viscosity Washable

liquids1, OSP

Washer fluid flow rate

Outlet Diameter

The distance of the outlet from the substrate0, 45 m

5 Depth of vacuum to the source of which a drain hole is connected (residual pressure) 6.39 kPa Continuous distance

0 rod guide from the substrate 0.3 TO-2 m Coating speed 4 m / s The distance of the end of the solid guide for the edge 0.3 m from the substrate causes the formation of a small neck at the curtain during its free fall onto the moving substrate. When near the lower end of the edge guide

Whether the washer fluid was in the area of the edge portion of the curtain, the distinct layered profile of the edge of the coating was characterized by uniformity and satisfactory. This provided the possibility of drying the edge of the coating in the machine for applying it in the same

point as the rest of the coating. Moreover, the uncovered edge of the substrate caused the complete elimination or significant reduction in the amount of coating in the embossed area. It was found that the removal of washer fluid has no effect on the stability of the falling curtain.

The implementation of the invention allows a wide range to be selected for the width of the slit, the length and the inner diameter of the guide for the edge in order to supply the desired amount of washing fluid and the edges of the curtain during its free fall. Measuring the flow rate of the washer fluid and regulating the operation of the vacuum source connected to the contact point makes it possible to adjust the amount of

washer fluid removed at the bottom of the edge guide to maintain curtain stability, which is independent of the flow rate of the curtain and the speed of coating.

Claims (5)

1. A method of applying to a substrate a coating of a liquid composition in the form of a freely falling curtain, comprising forming a layer of a liquid coating composition, moving the substrate through a coating zone, forming from a layer of a liquid composition for coating a curtain freely falling on the substrate across its direction of movement and limited along the edges of the edge guides l located one from the other at a distance smaller than the width of the substrate, and the supply of washing fluid to both edge guides defining the width of the free falling curtain, characterized in that, in order to increase the quality of the coating of the substrate is removed from the edges of the washer fluid curtain by connecting a vacuum source to the guide for the edges near the contact point of free falling curtain to the movable substrate. 2. The method according to p. 1. characterized in that the layer for coating the substrate is formed in the form of a composite Z Z 10 5 5 0 a layer formed by several layers of liquid compositions. 3. The method according to paragraphs. 1 and 2, characterized in that the amount of fluid removed from the edges of the freely falling curtain is controlled by the amount of washer fluid supplied to each rail and the pressure in the vacuum source, while the amount of washer fluid is in the range 0.833 x, 333 x x10 m / s, and the pressure in the vacuum source is in the range of 1.23-9.84 kPa. 4. The method according to paragraphs. 1-3, characterized in that the lower ends of the rails are set at a distance of 0.2 m from the substrate. 5. The method according to paragraphs. 1-4, characterized in that the washer fluid is supplied inside the guides for the edges made in the form of hollow tubes with a slit width (0.7-4.0) m facing the curtain, and the vacuum source is connected to the curved bottom end sections of guides with an internal radius of curvature (0.3-1.2) 10 m. L & FIG. I 1 / , (S / s / sSf7f // h x h x y v v h h x h ± and FIG. b I / & 7 n 1836655 fie.Yu Fig, "